A reflow proportion control device for a double reflow AOA process

Abstract

The application discloses a backflow ratio control device for a double-backflow AOA process, relates to the technical field of sewage treatment, and comprises, from left to right, an anaerobic tank, an aerobic tank, an anoxic tank and a secondary sedimentation tank. The anaerobic tank, the aerobic tank, the anoxic tank and the secondary sedimentation tank are connected in series through a sewage transfer assembly. The device further comprises a sludge discharge position control mechanism, an upper-layer sludge backflow mechanism and a lower-layer sludge backflow mechanism. The sludge discharge position control mechanism comprises a sludge discharge rotating pipe, and the bottom end of the sludge discharge rotating pipe is rotationally connected to the bottom center of the secondary sedimentation tank. The backflow ratio control device for the double-backflow AOA process can backflow the sludge close to the lower layer in the secondary sedimentation tank to the anoxic tank and backflow the sludge close to the upper layer in the secondary sedimentation tank to the anaerobic tank, so that the sludge close to the lower layer in the secondary sedimentation tank with a high nitrate content is prevented from being backflowed to the anaerobic tank. The sludge backflowed to the anaerobic tank and the anoxic tank has a high mixing efficiency with the sewage entering the tank or the original sewage in the tank, and the sewage treatment efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a reflux ratio control device for a dual reflux AOA process. Background Technology

[0002] The sludge double recirculation AOA process is a new and efficient denitrification process. The process includes an anaerobic tank, an aerobic tank, an anoxic tank and a secondary sedimentation tank connected in sequence. The sludge in the secondary sedimentation tank is recirculated in two ways: one way is recirculated to the front end of the anaerobic tank and the other way is recirculated to the front end of the anoxic tank.

[0003] In this process, some of the returned sludge is introduced into the anaerobic tank to maintain the concentration balance of microorganisms. Under anaerobic conditions, these microorganisms decompose organic matter, releasing intracellular orthophosphate and simultaneously generating energy by breaking down glycogen to store internal carbon sources within their cells. These internal carbon sources are then utilized in the anoxic tank for denitrification, thereby reducing dependence on external carbon sources and improving nitrogen removal efficiency.

[0004] The second return sludge to the anoxic tank provides an internal carbon source for denitrification and also increases the number of denitrifying bacteria in the anoxic tank. The denitrifying bacteria in the return sludge can utilize the internal carbon source and other organic matter in the anoxic environment of the anoxic tank to carry out denitrification, converting nitrates into nitrogen gas. This process requires no external carbon source, has high nitrogen removal efficiency, and is especially suitable for denitrification of wastewater with a low carbon-to-nitrogen ratio.

[0005] Currently, many wastewater treatment plants do not distinguish between upper and lower sludge layers during sludge return. This can easily lead to the return of lower sludge with higher nitrate content to the anaerobic tank, which can affect the growth and activity of anaerobic microorganisms, interfere with the anaerobic phosphorus release reaction, and result in low mixing efficiency between the sludge returned to the anaerobic and anoxic tanks and the original wastewater, thus affecting the nitrogen and phosphorus removal efficiency of the wastewater. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the existing defects and provide a reflux ratio control device for a dual-reflux AOA process. This device can reflux sludge near the lower layer of the secondary sedimentation tank to the anoxic tank, and reflux sludge near the upper layer of the secondary sedimentation tank to the anaerobic tank. This avoids refluxing sludge with high nitrate content near the lower layer of the secondary sedimentation tank into the anaerobic tank, thus avoiding interference with the growth and activity of anaerobic microorganisms and the anaerobic phosphorus release reaction. The sludge refluxed to the anaerobic and anoxic tanks mixes efficiently with the wastewater entering the tanks or the original wastewater in the tanks, which is beneficial to improving the nitrogen and phosphorus removal efficiency of the wastewater. This can effectively solve the problems in the background technology.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a reflux ratio control device for a dual-reflux AOA process, comprising an anaerobic tank, an aerobic tank, an anoxic tank, and a secondary sedimentation tank arranged sequentially from left to right, wherein the anaerobic tank, aerobic tank, anoxic tank, and secondary sedimentation tank are connected in series via a wastewater transfer assembly, and further comprising:

[0008] The sludge discharge position control mechanism includes a sludge discharge rotating pipe. The bottom center of the secondary sedimentation tank is rotatably connected to the bottom end of the sludge discharge rotating pipe. The sludge discharge rotating pipe has a lower sludge discharge hole at the bottom of the secondary sedimentation tank. The sludge discharge rotating pipe has an upper sludge discharge hole in a ring array above the lower sludge discharge hole. A baffle is provided in the sludge discharge rotating pipe between the upper and lower sludge discharge holes.

[0009] The upper sludge return mechanism is connected to the top of the sludge discharge pipe at one end, and the other end of the upper sludge return mechanism extends to the front end of the water inlet in the anaerobic tank.

[0010] The lower sludge return mechanism is connected to the bottom of the sludge discharge pipe at one end, and the other end of the lower sludge return mechanism extends to the front end of the inlet water in the anoxic tank.

[0011] External wastewater is transferred into the anaerobic tank via a wastewater transfer assembly at the inlet. Anaerobic reactions then occur within the anaerobic tank. Wastewater from the anaerobic tank is then transferred to the aerobic tank via the same assembly for aerobic reactions. Wastewater from the aerobic tank is then transferred to the anoxic tank via the same assembly for further reactions. Wastewater from the anoxic tank is then transferred to the secondary sedimentation tank via the same assembly for settling. Sludge settles at the bottom of the secondary sedimentation tank. The sludge from the secondary sedimentation tank is then returned to the anaerobic and anoxic tanks via a sludge discharge control mechanism, an upper sludge return mechanism, and a lower sludge return mechanism, respectively. This replenishes the activated sludge lost from the anaerobic and anoxic tanks due to effluent discharge, ensuring that the activated sludge in the reaction tanks remains stable within a reasonable range. This provides sufficient biomass support for microbial degradation of organic matter. Generally, the return process is... The sludge return ratio to the anaerobic tank is typically 50% to 100%, while the return ratio to the anoxic tank is 30% to 100%. Adjusting the sludge return ratio optimizes the microbial metabolic pathway, fully utilizes the raw water carbon source, and reduces the need for external reagents, thereby achieving the goal of deep nitrogen and phosphorus removal. The lower sludge return mechanism uses the area below the baffle in the sludge discharge pipe and the lower sludge discharge hole to suck up the lower layer of sludge settled in the secondary sedimentation tank and send it into the anoxic tank. The upper sludge return mechanism uses the area above the baffle in the sludge discharge pipe and the upper sludge discharge hole to suck up the upper layer of sludge settled in the secondary sedimentation tank and send it into the anaerobic tank. The rotating power component drives the sludge discharge pipe to rotate within the secondary sedimentation tank, which in turn drives the lower sludge discharge hole to rotate, expanding the range for sucking up the lower layer of settled sludge.

[0012] Furthermore, the sludge discharge position control mechanism also includes a sludge scraper and a sludge discharge cover and a support return pipe. The lower sludge discharge hole is connected to two sludge scraper and sludge discharge covers through two support return pipes. The two sludge scraper and sludge discharge covers are arranged side by side, and the bottom of the two sludge scraper and sludge discharge covers is close to the bottom of the secondary sedimentation tank. When the sludge discharge pipe rotates in the secondary sedimentation tank, it drives the sludge scraping and sludge discharge hood to rotate via the support return pipe. Two parallel sludge scraping and sludge discharge hoods form a scraper that can scrape up the sludge at the bottom of the secondary sedimentation tank. When the lower sludge return mechanism is working, the lower layer of sludge settled in the secondary sedimentation tank enters the sludge scraping and sludge discharge hood, and then enters the area below the baffle in the sludge discharge pipe through the support return pipe and the lower sludge discharge hole. Then, it is sent to the left end of the anoxic tank through the lower sludge return mechanism, realizing the sludge return to the anoxic tank. As the rotating power component drives the sludge discharge pipe to rotate in the secondary sedimentation tank, it drives the sludge scraping and sludge discharge hood to rotate at the bottom of the secondary sedimentation tank, which can quickly guide the sludge at the bottom of the secondary sedimentation tank into the sludge scraping and sludge discharge hood. Then, it is pumped away through the support return pipe and the lower sludge return mechanism. The sludge scraping and sludge discharge hood, together with the rotating power component and the sludge discharge pipe, can also play a sludge scraping role, which can ensure that the lower sludge return mechanism can fully pump away the lower layer of sludge settled in the secondary sedimentation tank.

[0013] Furthermore, the sludge discharge position control mechanism also includes a conical sludge occupant sleeve and a sealing ring. The conical sludge occupant sleeve is fitted onto the bottom of the sludge discharge pipe within the secondary sedimentation tank, and a sealing ring is installed between the bottom of the conical sludge occupant sleeve and the bottom of the secondary sedimentation tank. The conical sludge occupant sleeve is used to occupy the area within the conical structure at the bottom of the secondary sedimentation tank, preventing sludge from settling in this area and making it difficult for the sludge scraper and discharge hood to remove the sludge from this area. The sealing ring prevents sewage from entering the center bottom of the secondary sedimentation tank, and together with the sealing bearing, prevents sewage from leaking from the connection between the secondary sedimentation tank and the sludge discharge pipe.

[0014] Furthermore, the upper sludge return mechanism includes an upper sludge pumping assembly and an anaerobic tank sludge conveying assembly. The top end of the sludge discharge pipe is connected to one end of the upper sludge pumping assembly, and the other end of the upper sludge pumping assembly is connected to the front end of the return sludge layer switching mechanism. The right end of the return sludge layer switching mechanism is connected to one end of the anaerobic tank sludge conveying assembly, and the other end of the anaerobic tank sludge conveying assembly extends to the front end of the anaerobic tank inlet.

[0015] Furthermore, the lower sludge return mechanism includes a lower sludge pumping assembly and an anoxic tank sludge conveying assembly. The bottom end of the sludge discharge pipe is connected to one end of the lower sludge pumping assembly, the other end of the lower sludge pumping assembly is connected to the rear end of the return sludge layer switching mechanism, the left end of the return sludge layer switching mechanism is connected to one end of the anoxic tank sludge conveying assembly, and the other end of the anoxic tank sludge conveying assembly extends to the front end of the inlet water in the anoxic tank.

[0016] The upper sludge pumping assembly, in conjunction with the upper sludge discharge hole on the sludge discharge transfer pipe, extracts the upper sludge settled in the secondary sedimentation tank. The lower sludge pumping assembly, in conjunction with the lower sludge discharge hole on the sludge discharge transfer pipe, the sludge scraper and sludge discharge cover, and the supporting return pipe, extracts the lower sludge settled in the secondary sedimentation tank. Under normal circumstances, the return sludge layer switching mechanism sends the upper sludge pumped by the upper sludge pumping assembly into the anaerobic tank through the anaerobic tank sludge conveying assembly, and sends the lower sludge pumped by the lower sludge pumping assembly into the anoxic tank through the anoxic tank sludge conveying assembly.

[0017] When the sludge concentration in the anaerobic tank is low, the function of the sludge return layer switching mechanism is switched to: sending the upper sludge pumped by the upper sludge pumping component into the anoxic tank through the anoxic tank sludge conveying component, and sending the lower sludge pumped by the lower sludge pumping component into the anaerobic tank through the anaerobic tank sludge conveying component. While maintaining the original sludge return ratio, the high concentration of the lower sludge in the secondary sedimentation tank can quickly increase the sludge concentration and microbial concentration in the anaerobic tank. It should be noted that this method is suitable for situations where the overall nitrate content in the secondary sedimentation tank is low.

[0018] Furthermore, the reflux sludge layer switching mechanism includes a housing, a circular switching groove, a switching plate, a circular plate, a housing cover, and a switching motor. The housing has a circular switching groove in the middle, and a housing cover is installed on the top of the housing. The switching motor is installed in the middle of the housing cover. The bottom output shaft of the switching motor extends into the circular switching groove and is fixedly connected to the top center of the switching plate. Both ends of the switching plate are respectively provided with arc surfaces that cooperate with the sidewalls of the circular switching groove. Two circular plates are respectively provided on the upper and lower sides of the switching plate. When the reflux stops, the upper and lower sludge pumping components stop working. The switching motor keeps the switching plate in a horizontal position. The two arc surfaces at both ends of the switching plate block the round holes on the left and right sides of the shell. When the reflux starts, the switching motor drives the switching plate and the two round plates to rotate counterclockwise by 45 degrees. The first sludge guide chamber connects the upper sludge pumping component and the anaerobic tank sludge conveying component. The sludge pumped out by the upper sludge pumping component is sent into the anaerobic tank through the anaerobic tank sludge conveying component. The second sludge guide chamber connects the lower sludge pumping component and the anoxic tank sludge conveying component. The sludge pumped out by the lower sludge pumping component is sent into the anoxic tank through the anoxic tank sludge conveying component.

[0019] When the sludge and microbial concentrations in the anaerobic tank are low, the switching motor drives the switching plate and two circular plates to rotate 90 degrees clockwise. Sludge guide chamber one connects the upper sludge pumping component and the anoxic tank sludge conveying component. The sludge pumped out by the upper sludge pumping component is sent into the anoxic tank through the anoxic tank sludge conveying component. Sludge guide chamber two connects the lower sludge pumping component and the anaerobic tank sludge conveying component. The sludge pumped out by the lower sludge pumping component is sent into the anaerobic tank through the anaerobic tank sludge conveying component.

[0020] Furthermore, it also includes a return sludge influent convection mixing mechanism, which includes a mixing tank, a control solenoid valve, and a discharge channel. The anaerobic tank sludge conveying component located in the anaerobic tank and the anoxic tank sludge conveying component located in the anoxic tank are respectively connected to the bottom inlet of the two mixing tanks through two control solenoid valves. A discharge channel is opened in the middle of the right side of each mixing tank, and the top of each mixing tank is connected to the corresponding sewage transfer component. When the control solenoid valve is opened, the sludge from the anaerobic tank sludge conveying assembly and the anoxic tank sludge conveying assembly respectively enters the bottom of the two mixing tanks. Specifically: the anaerobic tank sludge conveying assembly sends sludge to the bottom of the mixing tank in the anaerobic tank, while the wastewater transfer assembly sends external wastewater to the top of the mixing tank in the anaerobic tank. The external wastewater mixes rapidly with the sludge at the bottom of the mixing tank in the anaerobic tank and is discharged into the anaerobic tank through the discharge channel. Similarly, the anoxic tank sludge conveying assembly sends sludge to the bottom of the mixing tank in the anoxic tank, and the wastewater transfer assembly between the aerobic and anoxic tanks sends wastewater from the aerobic tank to the top of the mixing tank in the anoxic tank. Here, the wastewater mixes rapidly with the sludge at the bottom of the mixing tank in the anoxic tank and is discharged into the anoxic tank through the discharge channel. This process promotes rapid mixing of the returned sludge with the original wastewater in the tanks, which helps improve wastewater treatment efficiency.

[0021] Furthermore, the reflux sludge influent convection mixing mechanism also includes a semi-circular arc baffle, horizontal baffles, mud holes, and water holes. A semi-circular arc baffle is provided in the middle of the left side of the mixing tank. Water holes are evenly distributed in the upper half of the semi-circular arc baffle, and mud holes are evenly distributed in the lower half of the semi-circular arc baffle. The upper and lower ends of the semi-circular arc baffle are respectively fixedly connected to the left ends of two horizontal baffles, and the right ends of the two horizontal baffles are respectively connected to the upper and lower ends of the discharge channel. The semi-circular arc baffle and the two horizontal baffles constitute a convection mixing chamber.

[0022] Sludge enters the sludge inlet chamber of the mixing tank through the control solenoid valve. The sludge is dispersed into the convection mixing chamber through the sludge holes. Wastewater enters the water inlet chamber of the mixing tank through the wastewater transfer component. Then the wastewater is dispersed into the convection mixing chamber through the water holes. The dispersed wastewater and dispersed sludge are fully convectioned and quickly mixed, resulting in a uniform mixture. This process is suitable for situations where wastewater is transported into the mixing tank through the wastewater transfer component.

[0023] Furthermore, the system also includes a sludge return influent mixing mechanism. This mechanism comprises a rotating drum, an outer mixing frame, an inner mixing frame, and a rotating shaft. A longitudinally mounted rotating drum is rotatably installed at the front center of each mixing chamber. A rotating shaft is rotatably connected inside each rotating drum. The rear end of the rotating drum is connected to the outer mixing frame, and the rear end of the rotating shaft is connected to the inner mixing frame. The inner mixing frame is located inside the outer mixing frame, and both the outer and inner mixing frames are located within their respective convection mixing chambers. The front ends of the rotating drum and the rotating shaft are connected to opposing drive components. The opposing drive components drive the rotating drum and rotating shaft to rotate in opposite directions, thereby causing the outer and inner mixing frames to rotate in opposite directions within the convection mixing chambers. This facilitates thorough mixing of the sludge and wastewater within the convection mixing chambers and promotes rapid mixing of the sludge and wastewater.

[0024] Furthermore, it also includes a sludge return discharge agitation mechanism, which includes an agitation vertical pipe. The anaerobic tank sludge conveying component located in the anaerobic tank and the anoxic tank sludge conveying component located in the anoxic tank are respectively connected to the bottom ends of two bends. A control solenoid valve is installed in the middle of each bend. The top end of each bend is connected to the bottom end of the agitation vertical pipe through a rotary joint. The top end of each agitation vertical pipe is connected to an agitation drive component. The side of each agitation vertical pipe is connected to a vertical agitation pipe through a radial pipe. Sludge discharge troughs are vertically and equidistantly opened on the side of the agitation pipe away from the agitation vertical pipe. When the wastewater transfer component does not deliver wastewater into the mixing tank but the sludge is returned to the mixing tank, control solenoid valve one is closed and control solenoid valve two is opened. The sludge is sent into the stirring vertical pipe through the bend and rotary joint three, and then into the stirring pipe through the radial pipe. It is then dispersed into the corresponding anaerobic or anoxic tank through the sludge discharge trough. The stirring drive component drives the stirring vertical pipe, radial pipe and stirring pipe to rotate. Rotary joint three ensures that the rotating stirring vertical pipe and bend can still have medium conduction. The radial pipe and stirring pipe are also used as stirring rods. The sludge dispersed into the tank through the sludge discharge trough is fully stirred with the wastewater in the tank, so as to achieve full mixing of wastewater and sludge.

[0025] Compared with existing technologies, the beneficial effects of this reflux ratio control device for dual reflux AOA process are:

[0026] 1. This recirculation ratio control device for the dual-recirculation AOA process allows sludge from the secondary sedimentation tank to be recirculated back to the anaerobic and anoxic tanks via a sludge discharge position control mechanism, an upper sludge recirculation mechanism, and a lower sludge recirculation mechanism. This replenishes the activated sludge lost from the anaerobic and anoxic tanks due to effluent discharge, ensuring that the activated sludge in the reaction tank remains stable within a reasonable range. This provides sufficient biomass support for microbial degradation of organic matter. Generally, the sludge recirculation ratio to the anaerobic tank is 50% to 100%, and the sludge recirculation ratio to the anoxic tank is 30% to 100%. This optimizes the microbial metabolic pathway, fully utilizes the carbon source of the raw water, reduces the need for external reagents, and thus achieves the goal of deep nitrogen and phosphorus removal.

[0027] 2. This reflux ratio control device for the dual-reflux AOA process has a lower sludge reflux mechanism that sucks away the lower layer of sludge settled in the secondary sedimentation tank and sends it into the anoxic tank through the area below the baffle in the sludge discharge pipe and the lower sludge discharge hole. The upper sludge reflux mechanism sucks away the upper layer of sludge settled in the secondary sedimentation tank and sends it into the anaerobic tank through the area above the baffle in the sludge discharge pipe and the upper sludge discharge hole. The rotary power component drives the sludge discharge pipe to rotate in the secondary sedimentation tank. The lower sludge discharge hole, together with the supporting reflux pipe and the sludge scraper hood, can expand the range of lower sludge suction. The sludge scraper hood, together with the rotary power component and the sludge discharge pipe, can also play a sludge scraping role, which can ensure that the lower sludge reflux mechanism fully removes the lower sludge settled in the secondary sedimentation tank.

[0028] 3. The reflux ratio control device for the dual-reflux AOA process detects the sludge concentration in the anaerobic tank. When the sludge concentration and microbial concentration in the anaerobic tank are low, the function of the reflux sludge layer switching mechanism is switched to: sending the upper sludge pumped by the upper sludge pumping component into the anoxic tank through the anoxic tank sludge conveying component, and sending the lower sludge pumped by the lower sludge pumping component into the anaerobic tank through the anaerobic tank sludge conveying component. While maintaining the original sludge reflux ratio, the high concentration of the lower sludge in the secondary sedimentation tank can quickly increase the sludge concentration and microbial concentration in the anaerobic tank.

[0029] 4. Sludge enters the sludge inlet chamber of the mixing tank through the control solenoid valve. The sludge is dispersed into the convection mixing chamber through the sludge holes. Wastewater enters the water inlet chamber of the mixing tank through the wastewater transfer component. Then, the wastewater is dispersed into the convection mixing chamber through the water holes. The dispersed wastewater and dispersed sludge are fully convectioned and quickly mixed. The opposing drive component drives the rotating drum and rotating shaft to rotate in opposite directions, thereby driving the mixing outer frame and mixing inner frame to rotate in opposite directions in the convection mixing chamber. This facilitates the full mixing of sludge and wastewater in the convection mixing chamber and promotes the rapid mixing of sludge and wastewater.

[0030] 5. The reflux ratio control device used in the dual-reflux AOA process can reflux the sludge near the lower layer of the secondary sedimentation tank to the anoxic tank, and reflux the sludge near the upper layer of the secondary sedimentation tank to the anaerobic tank. This avoids the sludge with high nitrate content near the lower layer of the secondary sedimentation tank from being refluxed into the anaerobic tank, thus avoiding interference with the growth and activity of anaerobic microorganisms and the anaerobic reaction. The sludge refluxed into the anaerobic and anoxic tanks mixes efficiently with the wastewater entering the tanks or the original wastewater in the tanks, which is beneficial to improving the nitrogen and phosphorus removal efficiency of the wastewater. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the reflux ratio control device for the dual reflux AOA process of the present invention;

[0032] Figure 2 For the present invention Figure 1A magnified view of the structure at point A in the middle;

[0033] Figure 3 For the present invention Figure 1 Top view of the structure;

[0034] Figure 4 This is a schematic cross-sectional view of the secondary sedimentation tank and the sludge discharge position control mechanism in this invention.

[0035] Figure 5 For the present invention Figure 4 A magnified schematic diagram of the structure at point B in the middle;

[0036] Figure 6 This is a partial structural schematic diagram of the sludge discharge position control mechanism in this invention;

[0037] Figure 7 This is an exploded structural diagram of the reflux mud layer switching mechanism in this invention;

[0038] Figure 8 This is a partial structural diagram of the present invention. Figure 1 ;

[0039] Figure 9 This is a partial structural diagram of the present invention. Figure 2 ;

[0040] Figure 10 This is a schematic cross-sectional view of the reflux sludge influent convection mixing mechanism in this invention.

[0041] Figure 11 For the present invention Figure 10 A magnified schematic diagram of the structure at point C in the middle;

[0042] In the diagram: 1 Secondary sedimentation tank; 2 Sludge discharge position control mechanism; 21 Secondary sedimentation tank crossbeam; 22 Crossbeam bearing; 23 Sludge discharge rotary pipe; 24 Driven gear; 25 Driven gear; 26 Control motor; 27 Sealed bearing I; 28 Conical sludge occupant sleeve; 29 Sealing ring I; 210 Baffle; 211 Upper sludge discharge hole; 212 Sludge scraper and discharge cover; 213 Supporting return pipe; 214 Lower sludge discharge hole; 3 Upper sludge return mechanism; 31 Rotary joint I; 32 Upper return pipe I; 3 3 Upper sludge discharge pump, 34 Upper sludge return pipe II, 35 Upper sludge return pipe III, 36 Upper sludge return solenoid valve, 37 Upper sludge flow meter, 4 Lower sludge return mechanism, 41 Rotary joint II, 42 Lower sludge return pipe I, 43 Lower sludge discharge pump, 44 Lower sludge return pipe II, 45 Lower sludge return pipe III, 46 Lower sludge return solenoid valve, 47 Lower sludge flow meter, 5 Return sludge layer switching mechanism, 51 Housing, 52 Circular switching groove, 53 Switching plate, 54 Circular plate, 55 Housing cover, 56 57. Bracket, 58. Switching motor, 59. Shell cover bolt, 6. Sealing ring II, 6. Return sludge inlet convection mixing mechanism, 61. Mixing box, 62. Box frame, 63. Control solenoid valve I, 64. Discharge channel, 65. Semi-circular arc baffle, 66. Horizontal baffle, 67. Mud hole, 68. Water hole, 7. Return sludge inlet mixing mechanism, 71. Sealed bearing II, 72. Rotary drum, 73. Bevel gear I, 74. Bevel gear II, 75. Drive bevel gear, 76. Mixing motor, 77. Motor base, 78. Mixing frame. 79 Mixing inner frame, 710 Rotating shaft, 8 Return sludge discharge agitation mechanism, 81 Bend, 82 Control solenoid valve II, 83 Rotary joint III, 84 Longitudinal beam, 85 Agitator motor, 86 Agitator vertical pipe, 87 Radial pipe, 88 Agitator pipe, 89 Sludge discharge trough, 9 Wastewater transfer assembly, 91 Wastewater pump, 92 Discharge pipe, 93 Inlet pipe, 11 Anaerobic tank, 12 Aerobic tank, 13 Anoxic tank, 14 Wastewater flow meter, 15 Ultrasonic sludge level gauge, 16 Sludge discharge pipe, 17 Sludge discharge solenoid valve. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1, please refer to Figures 1 to 11This embodiment provides a technical solution: a reflux ratio control device for a dual-reflux AOA process, comprising an anaerobic tank 11, an aerobic tank 12, an anoxic tank 13, and a secondary sedimentation tank 1 arranged sequentially from left to right. The secondary sedimentation tank 1 is cylindrical, and the bottom of the secondary sedimentation tank 1 has a conical structure. The anaerobic tank 11, aerobic tank 12, anoxic tank 13, and secondary sedimentation tank 1 are connected in series via a wastewater transfer assembly 9. A wastewater transfer assembly 9 is also installed at the left end of the anaerobic tank 11. The device also includes a sludge discharge position control mechanism 2, an upper sludge reflux mechanism 3, and a lower sludge reflux mechanism 4.

[0045] The wastewater transfer assembly 9 includes a wastewater pump 91, a discharge pipe 92, and an inlet pipe 93. The inlet of the wastewater pump 91 is connected to the inlet pipe 93, and the outlet of the wastewater pump 91 is connected to the discharge pipe 92. The wastewater transfer assembly 9 at the left end of the anaerobic tank 11 is used to send external wastewater into the left end of the anaerobic tank 11. The wastewater transfer assembly 9 between the anaerobic tank 11 and the aerobic tank 12 is used to send the wastewater in the anaerobic tank 11 into the aerobic tank 12. The wastewater transfer assembly 9 between the aerobic tank 12 and the anoxic tank 13 is used to send the wastewater in the aerobic tank 12 into the anoxic tank 13. The wastewater transfer assembly 9 between the anoxic tank 13 and the secondary sedimentation tank 1 is used to send the wastewater in the anoxic tank 13 into the secondary sedimentation tank 1.

[0046] It also includes a wastewater flow meter 14, which is installed on the discharge pipe 92 to monitor the flow rate of wastewater transferred by the wastewater transfer assembly 9 and to calculate the sludge return ratio.

[0047] The sludge discharge position control mechanism 2 includes a rotary power assembly, a sludge discharge pipe 23, a sealed bearing 27, a baffle 210, an upper sludge discharge hole 211, and a lower sludge discharge hole 214. The bottom center of the secondary sedimentation tank 1 is rotatably connected to the bottom end of the sludge discharge pipe 23 through the sealed bearing 27. The top of the sludge discharge pipe 23 is connected to the rotary power assembly. The lower sludge discharge hole 214 is opened at the bottom of the secondary sedimentation tank 1. The upper sludge discharge hole 211 is arranged in a ring array above the lower sludge discharge hole 214 in the sludge discharge pipe 23. A baffle 210 is provided in the sludge discharge pipe 23 between the upper sludge discharge hole 211 and the lower sludge discharge hole 214.

[0048] The sludge discharge position control mechanism 2 also includes a secondary sedimentation tank crossbeam 21 and a crossbeam bearing 22. The secondary sedimentation tank crossbeam 21 is installed on the top of the secondary sedimentation tank 1. The middle part of the secondary sedimentation tank crossbeam 21 is rotatably connected to the top of the sludge discharge pipe 23 through the crossbeam bearing 22. The secondary sedimentation tank crossbeam 21 and the crossbeam bearing 22 improve the stability of the sludge discharge pipe 23 when it rotates.

[0049] It also includes an ultrasonic sludge level gauge 15. An ultrasonic sludge level gauge 15 is installed on the crossbeam 21 of the secondary sedimentation tank. The ultrasonic sludge level gauge 15 is close to the inner wall of the secondary sedimentation tank 1. The ultrasonic sludge level gauge 15 is used to monitor the sludge thickness in the secondary sedimentation tank 1. The sludge return ratio can be controlled and changed according to the sludge thickness in the secondary sedimentation tank 1.

[0050] The rotating power assembly includes a driven gear 24, a driving gear 25, and a control motor 26. The driven gear 24 is fixedly installed on the top of the sludge discharge pipe 23. The control motor 26 is installed on the crossbeam 21 of the secondary sedimentation tank. The driving gear 25 is installed on the output shaft of the control motor 26. The driving gear 25 is meshed with the driven gear 24. When the control motor 26 works, it drives the sludge discharge pipe 23 to rotate through the transmission of the driven gear 24 and the driving gear 25.

[0051] The sludge discharge position control mechanism 2 also includes a sludge scraper and sludge discharge hood 212 and a support return pipe 213. The lower sludge discharge hole 214 is connected to the two sludge scraper and sludge discharge hoods 212 via the two support return pipes 213. The two sludge scraper and sludge discharge hoods 212 are arranged side-by-side, with their bottoms pressed against the bottom of the secondary sedimentation tank 1. When the sludge discharge pipe 23 rotates within the secondary sedimentation tank 1, it can drive the sludge scraper and sludge discharge hoods 212 to rotate via the support return pipes 213. The two parallel sludge scraper and sludge discharge hoods 212 form a scraper that can scrape up the sludge at the bottom of the secondary sedimentation tank 1. When the lower sludge return mechanism 4 operates, the lower sludge settled in the secondary sedimentation tank 1 enters the sludge scraper and sludge discharge hood 212, and then enters the area below the baffle 210 within the sludge discharge pipe 23 via the support return pipes 213 and the lower sludge discharge hole 214. Finally, it is sent into the anoxic tank 13 via the lower sludge return mechanism 4. On the left, sludge is returned to the anoxic tank 13. As the rotating power component drives the sludge discharge pipe 23 to rotate in the secondary sedimentation tank 1, the sludge scraper and sludge discharge cover 212 rotates at the bottom of the secondary sedimentation tank 1. This allows the sludge at the bottom of the secondary sedimentation tank 1 to be quickly introduced into the sludge scraper and sludge discharge cover 212. Then, it is pumped away through the supporting return pipe 213 and the lower sludge return mechanism 4. The sludge scraper and sludge discharge cover 212, together with the rotating power component and the sludge discharge pipe 23, can also play the role of scraping sludge, which can ensure that the lower sludge return mechanism 4 fully pumps away the sludge settled in the lower layer of the secondary sedimentation tank 1.

[0052] The sludge discharge position control mechanism 2 also includes a conical sludge occupant sleeve 28 and a sealing ring 29. The sludge discharge pipe 23 is located at the bottom of the secondary sedimentation tank 1 and is fitted with the conical sludge occupant sleeve 28. The top diameter of the conical sludge occupant sleeve 28 is smaller than the bottom diameter, and the upper sludge discharge hole 211 is located above the top of the conical sludge occupant sleeve 28. The support return pipe 213 passes through the conical sludge occupant sleeve 28, and a sealing ring 29 is installed between the bottom of the conical sludge occupant sleeve 28 and the bottom of the secondary sedimentation tank 1. There are two sealing rings 29, and the two sealing rings 29 have different diameters but are set at the same center. The bottom of the conical sludge occupant sleeve 28 and the bottom of the secondary sedimentation tank 1 are respectively provided with annular grooves that cooperate with the sealing rings 29. The conical sludge occupant sleeve 28 is used to occupy the area inside the conical structure at the bottom of the secondary sedimentation tank 1, so as to prevent sludge from settling in this area and making it difficult for the sludge scraper and sludge discharge cover 212 to remove the sludge in this area. The setting of the sealing ring 29 can prevent sewage from entering the center bottom of the secondary sedimentation tank 1. Together with the sealing bearing 27, it can prevent sewage from leaking from the connection between the secondary sedimentation tank 1 and the sludge discharge pipe 23.

[0053] One end of the upper sludge return mechanism 3 is connected to the top of the sludge discharge pipe 23, and the other end of the upper sludge return mechanism 3 extends to the front end of the water inlet in the anaerobic tank 11.

[0054] One end of the lower sludge return mechanism 4 is connected to the bottom end of the sludge discharge pipe 23, and the other end of the lower sludge return mechanism 4 extends to the front end of the water inlet in the anoxic tank 13.

[0055] The upper sludge return mechanism 3 includes an upper sludge pumping component and an anaerobic tank sludge conveying component. The top end of the sludge discharge pipe 23 is connected to one end of the upper sludge pumping component, the other end of the upper sludge pumping component is connected to the front end of the return sludge layer switching mechanism 5, the right end of the return sludge layer switching mechanism 5 is connected to one end of the anaerobic tank sludge conveying component, and the other end of the anaerobic tank sludge conveying component extends to the front end of the inlet water in the anaerobic tank 11.

[0056] The lower sludge return mechanism 4 includes a lower sludge pumping component and an anoxic tank sludge conveying component. The bottom end of the sludge discharge pipe 23 is connected to one end of the lower sludge pumping component, and the other end of the lower sludge pumping component is connected to the rear end of the return sludge layer switching mechanism 5. The left end of the return sludge layer switching mechanism 5 is connected to one end of the anoxic tank sludge conveying component, and the other end of the anoxic tank sludge conveying component extends to the front end of the inlet water in the anoxic tank 13.

[0057] The upper sludge pumping assembly, in conjunction with the upper sludge discharge hole 211 on the sludge discharge transfer pipe 23, extracts the upper sludge settled in the secondary sedimentation tank 1. The lower sludge pumping assembly, in conjunction with the lower sludge discharge hole 214 on the sludge discharge transfer pipe 23, the sludge scraper hood 212, and the supporting return pipe 213, extracts the lower sludge settled in the secondary sedimentation tank 1. Under normal circumstances, the return sludge layer switching mechanism 5 sends the upper sludge pumped by the upper sludge pumping assembly into the anaerobic tank 11 through the anaerobic tank sludge conveying assembly, and sends the lower sludge pumped by the lower sludge pumping assembly into the anoxic tank 13 through the anoxic tank sludge conveying assembly.

[0058] The sludge concentration in anaerobic tank 11 is monitored. When the sludge concentration and microbial concentration in anaerobic tank 11 are low, the function of the reflux sludge layer switching mechanism 5 is switched to: the upper sludge pumped by the upper sludge pumping component is sent into the anoxic tank 13 through the anoxic tank sludge conveying component, and the lower sludge pumped by the lower sludge pumping component is sent into the anaerobic tank 11 through the anaerobic tank sludge conveying component. While maintaining the original sludge reflux ratio, the sludge concentration and microbial concentration in anaerobic tank 11 can be rapidly increased due to the high concentration of the lower sludge in the secondary sedimentation tank 1. It should be noted that this situation is applicable when the overall nitrate content in the secondary sedimentation tank 1 is low.

[0059] The reflux sludge layer switching mechanism 5 includes a housing 51, a circular switching groove 52, a switching plate 53, a circular plate 54, a cover 55, and a switching motor 57. The housing 51 has a circular switching groove 52 in the middle, and a cover 55 is installed on the top of the housing 51. The switching motor 57 is installed in the middle of the cover 55. The bottom output shaft of the switching motor 57 extends into the circular switching groove 52 and is fixedly connected to the top center of the switching plate 53. The two ends of the switching plate 53 are respectively provided with arc surfaces that cooperate with the side walls of the circular switching groove 52. Two circular plates 54 are respectively provided on the upper and lower sides of the switching plate 53. The outer periphery of the two circular plates 54 cooperates with the inner wall of the circular switching groove 52. The area between the two circular plates 54 is divided by the switching plate 53 into a front sludge guide chamber one and a rear sludge guide chamber two.

[0060] The reflux sludge layer switching mechanism 5 also includes a bracket 56, a cover bolt 58, and a second sealing ring 59. The top of the housing 51 is fixedly connected to the cover 55 by the cover bolt 58. The switching motor 57 is mounted on the cover 55 by the bracket 56. A second sealing ring 59 is installed between the upper circular plate 54 and the top of the circular switching groove 52. The outer periphery of the upper circular plate 54 and the top of the circular switching groove 52 are respectively provided with annular mounting grooves that cooperate with the second sealing ring 59. The second sealing ring 59 is used to improve the sealing between the upper circular plate 54 and the circular switching groove 52.

[0061] When the backflow stops, the upper sludge pumping assembly and the lower sludge pumping assembly stop working. The switching motor 57 keeps the switching plate 53 in a horizontal position. The two arc surfaces at both ends of the switching plate 53 block the round holes on the left and right sides of the housing 51. When the backflow starts, the switching motor 57 works to drive the switching plate 53 and the two round plates 54 to rotate counterclockwise by 45 degrees. The first sludge guide chamber connects the upper sludge pumping assembly and the anaerobic tank sludge conveying assembly. The sludge pumped out by the upper sludge pumping assembly is sent into the anaerobic tank 11 through the anaerobic tank sludge conveying assembly. The second sludge guide chamber connects the lower sludge pumping assembly and the anoxic tank sludge conveying assembly. The sludge pumped out by the lower sludge pumping assembly is sent into the anoxic tank 13 through the anoxic tank sludge conveying assembly.

[0062] When the sludge concentration and microbial concentration in the anaerobic tank 11 are low, the switching motor 57 drives the switching plate 53 and the two circular plates 54 to rotate 90 degrees clockwise. The sludge diversion chamber one connects the upper sludge pumping component and the anoxic tank sludge conveying component. The sludge pumped out by the upper sludge pumping component is sent into the anoxic tank 13 through the anoxic tank sludge conveying component. The sludge diversion chamber two connects the lower sludge pumping component and the anaerobic tank sludge conveying component. The sludge pumped out by the lower sludge pumping component is sent into the anaerobic tank 11 through the anaerobic tank sludge conveying component.

[0063] The upper sludge pumping assembly includes a rotary joint 31, an upper return pipe 32, an upper sludge discharge pump 33, and an upper return pipe 34. The top end of the sludge discharge pipe 23 is connected to one end of the upper return pipe 32 through the rotary joint 31. The other end of the upper return pipe 32 is connected to the inlet of the upper sludge discharge pump 33. The outlet of the upper sludge discharge pump 33 is connected to the round hole at the front end of the housing 51 through the upper return pipe 34. The upper sludge discharge pump 33 serves as the power source for the upper sludge pumping assembly and is used to extract the upper sludge settled in the secondary sedimentation tank 1.

[0064] The anaerobic tank sludge conveying assembly includes an upper return pipe 35, an upper return solenoid valve 36, and an upper sludge flow meter 37. The round hole at the right end of the housing 51 is connected to one end of the upper return pipe 35, and the other end of the upper return pipe 35 extends to the left end inside the anaerobic tank 11. The upper return solenoid valve 36 and the upper sludge flow meter 37 are respectively installed on the upper return pipe 35. The upper return solenoid valve 36 is used to control the on / off state of the upper return pipe 35, and the upper sludge flow meter 37 is used to measure the flow rate of sludge in the upper return pipe 35.

[0065] The lower sludge pumping assembly includes a rotary joint 41, a lower return pipe 42, a lower sludge discharge pump 43, and a lower return pipe 44. The bottom end of the sludge discharge pipe 23 is connected to one end of the lower return pipe 42 via the rotary joint 41. The other end of the lower return pipe 42 is connected to the inlet of the lower sludge discharge pump 43. The outlet of the lower sludge discharge pump 43 is connected to one end of the lower return pipe 44, and the other end of the lower return pipe 44 is connected to the circular hole at the rear end of the housing 51. The lower sludge discharge pump 43 serves as the power source for the lower sludge pumping assembly and is used to pump the lower sludge settled in the secondary sedimentation tank 1.

[0066] The sludge conveying assembly for the anoxic tank includes a lower return pipe 45, a lower return solenoid valve 46, and a lower sludge flow meter 47. The round hole at the left end of the housing 51 is connected to one end of the lower return pipe 45, and the other end of the lower return pipe 45 extends to the left end of the anoxic tank 13. The lower return solenoid valve 46 and the lower sludge flow meter 47 are respectively installed on the lower return pipe 45. The lower return solenoid valve 46 is used to control the opening and closing of the lower return pipe 45, and the lower sludge flow meter 47 can measure the sludge flow rate in the lower return pipe 45.

[0067] During operation, external wastewater is transferred into anaerobic tank 11 via wastewater transfer component 9 at the left end of anaerobic tank 11. Anaerobic reaction then occurs within anaerobic tank 11. Wastewater from anaerobic tank 11 is then transferred to aerobic tank 12 via wastewater transfer component 9 for aerobic reaction. Wastewater from aerobic tank 12 is then transferred to anoxic tank 13 via wastewater transfer component 9 for reaction. Wastewater from anoxic tank 13 is then transferred to secondary sedimentation tank 1 via wastewater transfer component 9 for sedimentation. Sludge settles at the bottom of secondary sedimentation tank 1. The sludge from secondary sedimentation tank 1 is then returned to anaerobic tank 11 and anoxic tank 13 via sludge discharge position control mechanism 2, upper sludge return mechanism 3, and lower sludge return mechanism 4, respectively. This replenishes the activated sludge lost from anaerobic tank 11 and anoxic tank 13 due to effluent discharge, ensuring the activated sludge in the reaction tanks remains stable within a reasonable range, providing sufficient biomass support for microbial degradation of organic matter. The sludge return ratio to the anaerobic tank is generally 50% to 100%, while the sludge return ratio to the anoxic tank is 30% to 100%. Adjusting the sludge return ratio can optimize the microbial metabolic pathway, fully utilize the carbon source of the raw water, and reduce the need for external reagents, thereby achieving the goal of deep nitrogen and phosphorus removal. The lower sludge return mechanism 4 sucks away the lower layer of sludge settled in the secondary sedimentation tank 1 and sends it to the anoxic tank 13 through the area below the baffle 210 in the sludge discharge pipe 23 and the lower sludge discharge hole 214. The upper sludge return mechanism 3 sucks away the upper layer of sludge settled in the secondary sedimentation tank 1 and sends it to the anaerobic tank 11 through the area above the baffle 210 in the sludge discharge pipe 23 and the upper sludge discharge hole 211. The rotating power component drives the sludge discharge pipe 23 to rotate in the secondary sedimentation tank 1, which can drive the lower sludge discharge hole 214 to rotate, thus expanding the range of lower sedimented sludge suction.

[0068] Example 2, please refer to Figures 1 to 11 This embodiment provides a technical solution: a reflux ratio control device for a dual reflux AOA process. This embodiment is structurally similar to Embodiment 1, with the difference being:

[0069] It also includes a return sludge influent convection mixing mechanism 6, which includes a mixing tank 61, a control solenoid valve 63, and a discharge channel 64. The end of the anaerobic tank sludge conveying component located in the anaerobic tank 11 and the end of the anoxic tank sludge conveying component located in the anoxic tank 13 are respectively connected to the bottom inlet of the two mixing tanks 61 through two control solenoid valves 63. The right middle part of each mixing tank 61 is provided with a discharge channel 64, and the top of each mixing tank 61 is connected to the corresponding sewage transfer component 9.

[0070] The return sludge influent convection mixing mechanism 6 also includes a frame 62. The frame 62 is installed on the top of the mixing tank 61. The frame 62 in the anaerobic tank 11 is connected to the left end of the anaerobic tank 11, and the frame 62 in the anoxic tank 13 is connected to the left end of the anoxic tank 13.

[0071] Specifically, one end of the upper return pipe 35 located in the anaerobic tank 11 is connected to the bottom of the mixing box 61 in the anaerobic tank 11 through a control solenoid valve 63, and one end of the lower return pipe 45 located in the anoxic tank 13 is connected to the bottom of the mixing box 61 in the anoxic tank 13 through a control solenoid valve 63.

[0072] When the control solenoid valve 63 is opened, the sludge from the anaerobic tank sludge conveying assembly and the anoxic tank sludge conveying assembly respectively enters the bottom of the two mixing tanks 61. Specifically: the anaerobic tank sludge conveying assembly sends the sludge to the bottom of the mixing tank 61 in the anaerobic tank, and the wastewater transfer assembly 9 sends the external wastewater to the top of the mixing tank 61 in the anaerobic tank. The external wastewater mixes rapidly with the sludge at the bottom of the mixing tank 61 in the anaerobic tank and is discharged into the anaerobic tank through the discharge channel 64. The anoxic tank sludge conveying assembly sends the sludge to the bottom of the mixing tank 61 in the anoxic tank. The wastewater transfer assembly 9 between the aerobic tank 12 and the anoxic tank 13 sends the wastewater from the aerobic tank 12 to the top of the mixing tank 61 in the anoxic tank 13. The wastewater here mixes rapidly with the sludge at the bottom of the mixing tank 61 in the anoxic tank and is discharged into the anoxic tank 13 through the discharge channel 64. This promotes the rapid mixing of the returned sludge with the original wastewater in the tank, which helps to improve the wastewater treatment efficiency.

[0073] The sludge return influent convection mixing mechanism 6 also includes a semi-circular baffle 65, a horizontal baffle 66, mud holes 67, and water holes 68. A semi-circular baffle 65 is provided in the middle of the left side of the mixing box 61. Water holes 68 are evenly distributed in the upper half of the semi-circular baffle 65, and mud holes 67 are evenly distributed in the lower half of the semi-circular baffle 65. The upper and lower ends of the semi-circular baffle 65 are respectively fixedly connected to the left ends of two horizontal baffles 66, and the right ends of the two horizontal baffles 66 are respectively connected to the upper and lower ends of the discharge channel 64. The semi-circular baffle 65 and the two horizontal baffles 66 constitute a convection mixing chamber. The position above the convection mixing chamber in the mixing box 61 is the water inlet chamber, and the position below the convection mixing chamber in the mixing box 61 is the sludge inlet chamber.

[0074] Sludge enters the sludge inlet chamber of mixing tank 61 through solenoid valve 63. The sludge is dispersed into the convection mixing chamber through sludge hole 67. Wastewater enters the water inlet chamber of mixing tank 61 through wastewater transfer component 9. Then the wastewater is dispersed into the convection mixing chamber through water hole 68. The dispersed wastewater and dispersed sludge are fully convectioned and quickly mixed, resulting in a uniform mixture. This process is suitable for situations where wastewater is transported into mixing tank 61 by wastewater transfer component 9.

[0075] Example 3, please refer to Figures 1 to 11 This embodiment provides a technical solution: a reflux ratio control device for a dual reflux AOA process. This embodiment is structurally similar to Embodiment 2, with the difference being:

[0076] It also includes a sludge return water mixing mechanism 7, which includes a rotating drum 72, a counter-drive assembly, a mixing outer frame 78, a mixing inner frame 79, and a rotating shaft 710. The front middle section of each mixing chamber 61 is rotatably mounted with a longitudinal rotating drum 72. The rotating shaft 710 is rotatably connected inside the rotating drum 72. A sealing ring is provided between the rotating drum 72 and the rotating shaft 710 to prevent water leakage between the rotating drum 72 and the rotating shaft 710. The rear end of the rotating drum 72 is connected to the mixing outer frame 78, and the rear end of the rotating shaft 710 is connected to the mixing inner frame 79. The mixing inner frame 79 is located inside the mixing outer frame 78, and both the mixing outer frame 78 and the mixing inner frame 79 are located in the corresponding convection mixing chamber. The front end of the rotating drum 72 and the front end of the rotating shaft 710 are connected to the counter-drive assembly.

[0077] The opposing drive assembly includes a second sealed bearing 71, a first bevel gear 73, a second bevel gear 74, a drive bevel gear 75, a stirring motor 76, and a motor base 77. The front left side of the anaerobic tank 11 and the front left side of the anoxic tank 13 are rotatably connected to the front end of the rotating drum 72 via the second sealed bearing 71. The first bevel gear 73 is installed on the outer periphery of the front end of the rotating drum 72. The front end of the rotating shaft 710 extends to the outside of the front end of the rotating drum 72, and the second bevel gear 74 is installed on the outer periphery of the front end of the rotating shaft 710. The front left side of the anaerobic tank 11 and the front left side of the anoxic tank 13 are rotatably connected to the front end of the rotating drum 72 via the second sealed bearing 71. A stirring motor 76 is installed on the front left side of the anoxic pool 13 via a motor base 77. A drive bevel gear 75 is installed on the top output shaft of the stirring motor 76. The drive bevel gear 75 is located between the corresponding bevel gear 1 73 and bevel gear 2 74, and the front and rear sides of the drive bevel gear 75 are meshed with bevel gear 2 74 and bevel gear 1 73, respectively. When the stirring motor 76 works, it drives the drive bevel gear 75 to rotate. Through the transmission of bevel gear 1 73 and bevel gear 2 74, it drives the rotating drum 72 and the rotating shaft 710 to rotate in opposite directions.

[0078] The opposing drive assembly drives the rotating drum 72 and the rotating shaft 710 to rotate in opposite directions, thereby driving the mixing outer frame 78 and the mixing inner frame 79 to rotate in opposite directions in the convection mixing chamber, which is conducive to the full mixing of sludge and sewage in the convection mixing chamber and promotes the rapid mixing of sludge and sewage.

[0079] Example 4, please refer to Figures 1 to 11 This embodiment provides a technical solution: a reflux ratio control device for a dual reflux AOA process. This embodiment is structurally similar to Embodiment 3, with the difference being:

[0080] It also includes a sludge return discharge agitation mechanism 8, which comprises a bend 81, a control solenoid valve 82, a rotary joint 83, an agitation drive assembly, an agitation vertical pipe 86, a radial pipe 87, an agitation pipe 88, and a sludge discharge trough 89. The anaerobic tank sludge conveying assembly located in the anaerobic tank 11 and the anoxic tank sludge conveying assembly located in the anoxic tank 13 are respectively connected to the bottom ends of two bends 81. A control solenoid valve 82 is installed in the middle of each bend 81, and the top end of each bend 81 is connected to the agitation vertical pipe 86 via the rotary joint 83. At the bottom end of the tube 86, the top end of each agitating vertical tube 86 is connected to an agitating drive assembly. Each agitating vertical tube 86 has a vertical agitating tube 88 connected to its side via a radial tube 87. Mud discharge troughs 89 are vertically and equidistantly opened on the side of the agitating tube 88 away from the agitating vertical tube 86. Each agitating vertical tube 86 is provided with no less than six mud discharge troughs 89. The upper and lower ends of the agitating tube 88 are respectively closed. Three agitating tubes 88 are arranged around the outside of each agitating vertical tube 86. Each agitating tube 88 is connected to the corresponding agitating vertical tube 86 via two radial tubes 87.

[0081] The agitation drive assembly includes longitudinal beams 84 and agitation motors 85. Two longitudinal beams 84 are respectively installed at the top center of the anaerobic tank 11 and the top center of the anoxic tank 13. The middle parts of the two longitudinal beams 84 are rotatably connected to the top of the corresponding agitation vertical tubes 86 through bearings. The top of the agitation vertical tubes 86 is connected to the output shaft of the agitation motor 85. The agitation motor 85 is installed on the corresponding longitudinal beams 84 and is used to drive the agitation vertical tubes 86 to rotate.

[0082] When the wastewater transfer component 9 does not deliver wastewater to the mixing tank 61 but the sludge is returned to the mixing tank 61, the control solenoid valve 1 63 is closed and the control solenoid valve 2 82 is opened. The sludge is sent into the stirring vertical pipe 86 through the bend pipe 81 and the rotary joint 3 83, and then into the stirring pipe 88 through the radial pipe 87. It is then dispersed and discharged into the corresponding anaerobic tank 11 or anoxic tank 13 through the sludge discharge trough 89. The stirring drive component drives the stirring vertical pipe 86, radial pipe 87 and stirring pipe 88 to rotate. The rotary joint 3 83 ensures that the rotating stirring vertical pipe 86 and the bend pipe 81 can still have medium conduction. The radial pipe 87 and the stirring pipe 88 are also used as stirring rods. The sludge dispersed into the tank through the sludge discharge trough 89 and the wastewater in the tank are fully stirred to achieve full mixing of wastewater and sludge.

[0083] In other embodiments, please refer to Figures 1 to 11 The system also includes a sludge discharge pipe 16 and a sludge discharge solenoid valve 17. One end of the upper return pipe 35 near the housing 51 is connected to one end of the sludge discharge pipe 16, and the other end of the sludge discharge pipe 16 is connected to an external sludge filter press. The sludge discharge solenoid valve 17 is installed on the sludge discharge pipe 16, which closes the sludge discharge pipe 16 when sludge discharge is not required. When sludge needs to be discharged from the secondary sedimentation tank 1, the upper return solenoid valve 36 closes the upper return pipe 35, and the lower return solenoid valve 46 closes the lower return pipe 35. The sludge discharge solenoid valve 17 is opened, and the switching motor 57 operates, driving the switching plate 53 and the two circular plates 54 to rotate. When the sludge guide chamber 1 connects the upper return pipe 2 34 and the end of the upper return pipe 35 in the upper sludge pumping assembly, the upper sludge pumping assembly extracts the sludge from the upper layer of the secondary sedimentation tank 1 and then it enters the discharge pipe through the end of the upper return pipe 35. The sludge pipe 16 can discharge the upper layer of sludge from the secondary sedimentation tank 1 and then separate the sludge into mud and water through a sludge filter press. When the sludge guide chamber 2 connects the lower layer return pipe 2 44 in the lower layer sludge pumping assembly with the end of the upper layer return pipe 35, the lower layer sludge pumping assembly extracts the lower layer of sludge from the secondary sedimentation tank 1 and enters the sludge discharge pipe 16 through the end of the upper layer return pipe 35. This allows the lower layer of sludge from the secondary sedimentation tank 1 to be discharged and then separated into mud and water through a sludge filter press. This allows for selective control of the discharge of upper and lower layers of sludge from the secondary sedimentation tank 1.

[0084] It is worth noting that the sewage pump 91, sewage flow meter 14, ultrasonic sludge level gauge 15, control motor 26, switching motor 57, upper sludge discharge pump 33, upper reflux solenoid valve 36, lower sludge discharge pump 43, lower reflux solenoid valve 46, control solenoid valve 1 63, stirring motor 76, control solenoid valve 2 82, stirring motor 85, and sludge discharge solenoid valve 17 disclosed in the above embodiments are all controlled by an external PLC controller. The control method adopts the method commonly used in the prior art. The switching motor 57 is a servo motor, and the control motor 26, stirring motor 85, and stirring motor 76 are all geared motors.

[0085] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0086] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A reflux ratio control device for a dual-reflux AOA process, comprising an anaerobic tank (11), an aerobic tank (12), an anoxic tank (13), and a secondary sedimentation tank (1) arranged sequentially from left to right, wherein the anaerobic tank (11), aerobic tank (12), anoxic tank (13), and secondary sedimentation tank (1) are connected in series via a wastewater transfer assembly (9), characterized in that, Also includes: The sludge discharge position control mechanism (2) includes a sludge discharge pipe (23). The bottom center of the secondary sedimentation tank (1) is rotatably connected to the bottom end of the sludge discharge pipe (23). The sludge discharge pipe (23) is located at the bottom of the secondary sedimentation tank (1) and has a lower sludge discharge hole (214). The sludge discharge pipe (23) is located above the lower sludge discharge hole (214) and has an upper sludge discharge hole (211) arranged in a ring array. A baffle (210) is provided in the sludge discharge pipe (23) between the upper sludge discharge hole (211) and the lower sludge discharge hole (214). The upper sludge return mechanism (3) is connected to the top of the sludge discharge pipe (23) at one end, and the other end of the upper sludge return mechanism (3) extends to the front end of the water inlet in the anaerobic tank (11). The lower sludge return mechanism (4) is connected to the bottom end of the sludge discharge pipe (23) at one end, and the other end of the lower sludge return mechanism (4) extends to the front end of the water inlet in the anoxic tank (13). The upper sludge return mechanism (3) includes an upper sludge pumping component and an anaerobic tank sludge conveying component. The top end of the sludge discharge pipe (23) is connected to one end of the upper sludge pumping component, and the other end of the upper sludge pumping component is connected to the front end of the return sludge layer switching mechanism (5). The right end of the return sludge layer switching mechanism (5) is connected to one end of the anaerobic tank sludge conveying component, and the other end of the anaerobic tank sludge conveying component extends to the left end inside the anaerobic tank (11). The lower sludge return mechanism (4) includes a lower sludge pumping component and an anoxic tank sludge conveying component. The bottom end of the sludge discharge pipe (23) is connected to one end of the lower sludge pumping component. The other end of the lower sludge pumping component is connected to the rear end of the return sludge layer switching mechanism (5). The left end of the return sludge layer switching mechanism (5) is connected to one end of the anoxic tank sludge conveying component. The other end of the anoxic tank sludge conveying component extends to the left end of the anoxic tank (13). The reflux mud layer switching mechanism (5) includes a housing (51), a circular switching groove (52), a switching plate (53), a circular plate (54), a cover (55), and a switching motor (57). The housing (51) has a circular switching groove (52) in the middle, and a cover (55) is installed on the top of the housing (51). The switching motor (57) is installed in the middle of the cover (55). The bottom output shaft of the switching motor (57) extends into the circular switching groove (52) and is fixedly connected to the top center of the switching plate (53). The two ends of the switching plate (53) are respectively provided with arc surfaces that cooperate with the side walls of the circular switching groove (52). Two circular plates (54) are respectively provided on the upper and lower sides of the switching plate (53).

2. The reflux ratio control device for dual reflux AOA process according to claim 1, characterized in that: The sludge discharge position control mechanism (2) also includes a sludge scraper and sludge discharge cover (212) and a support return pipe (213). The lower sludge discharge hole (214) is connected to the two sludge scraper and sludge discharge covers (212) through the two support return pipes (213). The two sludge scraper and sludge discharge covers (212) are arranged side by side, and the bottom of the two sludge scraper and sludge discharge covers (212) is close to the bottom of the secondary sedimentation tank (1).

3. The reflux ratio control device for dual reflux AOA process according to claim 2, characterized in that: The sludge discharge position control mechanism (2) also includes a conical sludge occupant sleeve (28) and a sealing ring (29). The sludge discharge pipe (23) is fitted with the conical sludge occupant sleeve (28) at the bottom of the secondary sedimentation tank (1), and a sealing ring (29) is installed between the bottom of the conical sludge occupant sleeve (28) and the bottom of the secondary sedimentation tank (1).

4. The reflux ratio control device for dual reflux AOA process according to claim 1, characterized in that: It also includes a sludge influent convection mixing mechanism (6), which includes a mixing box (61), a control solenoid valve (63) and a discharge channel (64). The anaerobic tank sludge conveying component located in the anaerobic tank (11) and the anoxic tank sludge conveying component located in the anoxic tank (13) are respectively connected to the bottom inlet of the two mixing boxes (61) through two control solenoid valves (63). The right side of each mixing box (61) is provided with a discharge channel (64), and the top of each mixing box (61) is connected to the corresponding sewage transfer component (9).

5. The reflux ratio control device for dual reflux AOA process according to claim 4, characterized in that: The reflux sludge inlet convection mixing mechanism (6) also includes a semi-circular baffle (65), a horizontal baffle (66), mud holes (67) and water holes (68). A semi-circular baffle (65) is provided in the middle of the left side of the mixing box (61). Water holes (68) are evenly provided in the upper half of the semi-circular baffle (65), and mud holes (67) are evenly provided in the lower half of the semi-circular baffle (65). The upper and lower ends of the semi-circular baffle (65) are respectively fixedly connected to the left ends of two horizontal baffles (66), and the right ends of the two horizontal baffles (66) are respectively connected to the upper and lower ends of the discharge channel (64). The semi-circular baffle (65) and the two horizontal baffles (66) constitute a convection mixing chamber.

6. The reflux ratio control device for dual reflux AOA process according to claim 4, characterized in that: It also includes a sludge inlet mixing mechanism (7), which includes a rotating drum (72), a mixing outer frame (78), a mixing inner frame (79), and a rotating shaft (710). The front end of each mixing box (61) is rotatably mounted with a longitudinal rotating drum (72). The rotating shaft (710) is rotatably connected inside the rotating drum (72). The rear end of the rotating drum (72) is connected to the mixing outer frame (78), and the rear end of the rotating shaft (710) is connected to the mixing inner frame (79). The mixing inner frame (79) is located inside the mixing outer frame (78), and both the mixing outer frame (78) and the mixing inner frame (79) are located in the corresponding convection mixing chamber. The front end of the rotating drum (72) and the front end of the rotating shaft (710) are connected to opposing drive components.

7. The reflux ratio control device for dual reflux AOA process according to claim 4, characterized in that: It also includes a sludge discharge agitation mechanism (8), which includes an agitation vertical pipe (86). The end of the anaerobic tank sludge conveying component located in the anaerobic tank (11) and the end of the anoxic tank sludge conveying component located in the anoxic tank (13) are respectively connected to the bottom of two bends (81). A control solenoid valve (82) is installed in the middle of each bend (81). The top of each bend (81) is connected to the bottom of the agitation vertical pipe (86) through a rotary joint (83). The top of each agitation vertical pipe (86) is connected to an agitation drive component. The side of each agitation vertical pipe (86) is connected to a vertical agitation pipe (88) through a radial pipe (87). The agitation pipe (88) is provided with a sludge discharge trough (89) at equal vertical intervals on the side away from the agitation vertical pipe (86).

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